Ever wonder why you may look prettier in some photos and uglier in others, even with the same smile and the same lighting? It's all about the camera lens. These portraits -- taken by Stephen Eastwood -- show how this works.

If you have ever used a dating site and thought "damn, he/she looked so hot in those pictures! What happened?" or "wow! He/she looks a lot better in person," you know exactly what I'm talking about.

It's all about the lens distortion (which is also affected by the subject's distance to the camera). Lenses make the world look different than it does through your eyes. They bend light rays, capturing the scene within a certain field of view into a limited bi-dimensional frame: the photograph. Depending on the lens' focal length, the image will deform more or less, affecting how faces and objects look in photos.

The shorter the focal length, the more field of you view you can capture. With something like a 15mm fish eye lens, the effect is really obvious. Your face would be extremely deformed, like the rest of the environment. But as you go up, the distortion gets more subtle. Sometimes this distortion can make a face prettier than it actually is. Sometimes the effect makes a face uglier. Since this subtler distortion is not obvious, your mind just buys the image thinking that this is what the person looks like.

The same happens with larger focal lengths. At 350mm there's also a distortion: your face become flatter and wider.

In theory, shooting with something like a 135mm would produce the best, most accurate results, but there's no right or wrong here. It depends on your subject's anatomy. That's why some people are "photogenic" with certain cameras and at certain angles, and look horrible with others.

If you pay attention, you can really observe this effect in everyday photos taken with mobile phones and compact cameras. You can even see it without even changing the lens focal length. While taking photos with my iPhone on a recent trip, placing some people on the center of the frame made them look better, especially from a distance. Then, as I moved them to the sides of the frame, they looked sightly different. The distortion is more obvious near the sides, and it was enough to make them less attractive. The funny thing is that the contrary happened with me: I looked better on the sides than on the centre. Or maybe it was just that I had a horrible hangover the whole trip. [Stephen Eastwood via Petapixel]